Plugs are known from prior art that are mounted in a critical throat section of a chamber during storage of an engine.
Thus, for example, a blow-out plug according to U.S. Pat. No. 3,020,710 is made of synthetic rubber having high insulating properties. The plug is bonded in the portion located downstream of the nozzle throat section of a solid-propellant rocket engine.
A special covering is applied in the region where the plug is bonded to the nozzle. On an electric signal, the plug is separated along a thinned place by gas pressure, and the remaining part of the plug is burned out.
A disadvantage of this plug is that it is not dismountable during maintenance work.
Furthermore, during the process of engine storage it is often necessary to release the gases from the internal cavity of the combustion chamber.
This plug does not provide for the release of gases from the internal cavity of the combustion chamber, and this may result in a dangerous increase of the positive pressure in the internal cavity of the chamber during the process of engine storage.
A plug is also known from U.S. Pat. No. 3,390,529, which is mounted in the nozzle throat section of a rocket engine chamber. The attachment and sealing are provided by supplying a gaseous product into the internal cavity of the plug. Two valves are mounted on the plug, one of which makes it possible to maintain the pressure inside the chamber, and the other makes it possible to maintain the pressure inside the plug itself. One of the valves makes it possible to release the positive pressure from the internal cavity of the chamber.
The plug is blown out due to the pressure drop.
The construction of this plug is complex and it is heavy, which does not make it possible to effectively use it in this field of engineering.
A nozzle plug of a rocket engine chamber is known from U.S. Pat. No. 3,693,831. The plug is mounted in the nozzle throat section of the rocket engine chamber.
The plug is made of plastic in the form of a stopper of corresponding shape, wherein an annular groove is made in the stopper with an annular sealing element inserted in the groove. The sealing element is connected by a tube to an air source under pressure. A channel is made along the plug axis, and a metal tube (rod) is placed in this channel with a release valve mounted at the outlet thereof. When air under pressure is fed to the sealing element, the plug seals the chamber along the mating surfaces.
Vapors of the fuel and oxidizer are released from the internal cavity of the chamber by means of a release valve.
Such a system for removing the fuel and oxidizer vapors is ineffective because rapid blowing of the chamber is not possible.
This may also result in a dangerous increase of the positive pressure in the internal cavity of the chamber during storage of the engine.
Moreover, the known construction of the plug does not provide a guarantee that the plug will be blown out of the chamber at small pressure drops.
Furthermore, this system does not ensure the blowing of the chamber with gas at low pressure before the engine starts.
Finally, it is very difficult to produce the known plug with identical blow-out parameters.
The latter is especially important for the chambers of a multichamber LRE, where it is necessary to simultaneously blow out the plugs at the moment of engine start.